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cipher 

itatamprnttuctSfinc. 



Series 525 FloppyTape™ 

Cartridge Tape Drive 
Product Description 



TABLE OF CONTENTS 

Section Page 

1 INTRODUCTION 1-1 

1.1 Scope 1-1 

1 .2 Termino logy 1-1 

1.3 General Description 1-3 

1.4 Features 1-3 

2 SPECIFICATIONS & RELIABILITY 2-1 

2.1 Tape Specifications 2-1 

2.1.1 Recording Times 2-1 

2.1 .2 Positioning 2-1 

2.2 Reliability 2-2 

2.2.1 Mean Time Between Failures 2-2 

2.2.2 Mean Time To Repair 2-2 

2.2.3 Preventive Maintenance 2-2 

2.3 Data Integrity 2-3 

2.3.1 Media 2-3 

2.3.2 Recoverable Read Errors 2-3 

2.3.3 Non-Recoverable Read Errors 2-3 

2.3.4 Power Loss * 2-3 

3 FUNCTIONAL CHARACTERISTICS 3-1 

3.1 General Description 3-1 

3.2 Read/Write & Control Electronics 3-1 

3.3 Tape Drive Mechanism 3-3 

3.4 Read/Write Head Positioning Mechanism 3-3 

4 FUNCTIONAL DESCRIPTION 4-1 

4.1 Power Sequencing 4-1 

4.2 Stream Selection 4-1 

4.3 Head Load/Motor On 4-2 

4.4 Seg ment Accessing 4-2 

4.5 Step Out/Step In 4-4 

4.6 Read Operation 4-4 

4.7 Write Operation 4-5 

4.8 Recording Format 4-6 

5 INTERFACE SIGNALS 5-1 

5.1 Drive Interface 5-1 

5.2 Interface Signal Levels 5-4 

5.3 Input Control Signals 5-4 

5.4 Output Control Signals 5-5 

5.5 Data Line Signals 5-6 

5.5.1 Read Data Signal 5-6 

5.5.2 Write Data Signal 5-7 

Cipher Data Products, Inc. reserves 
the right to change specifications 
without notice. 
Copyright 1984 

i 



TABLE OF CONTENTS (Continued) 
Section Page 

6 PHYSICAL INTERFACE CONNECTION 6-1 

6.1 Interface Connector Locations 6-1 

6.2 Signal Connector Dimensions 6-1 

6.3 Recommended Cables and Connectors 6-2 

6.4 Termination 6-2 

6.5 Frame Ground 6-2 

7 PHYSICAL CHARACTERISTICS 7-1 

7.1 Mechanical Dimensions 7-1 

7.2 Weight 7-1 

7.3 Mounting 7-1 

8 ENVIRONMENTAL CHARACTERISTICS/POWER REQUIREMENTS 8-1 

8.1 Temperature 8-1 

8.2 Humidity 8-1 

8.3 Altitude 8-1 

8.4 Vibration 8-1 

8.5 Shock 8-1 

8.6 Air Quality 8-1 

8.7 Acoustical Noise 8-2 

8.8 DC Power 8-2 

8.9 Heat Dissipation 8-2 

8.10 Cooling 8-2 

9 APPLICATION NOTES 9-1 

9.1 General 9-1 

9.2 Hardware Considerations 9-2 

9.3 Encoding Techniques 9-4 

9.3.1 Single Density (FM) 9-4 

9.3.2 Double Density (MFM) 9-4 

9.4 Software Considerations 9-4 

9.4.1 Drive Selection 9-4 

9.4.2 Addressable Tracks (Segments) 9-4 

9.4.3 Number of Sectors 9-5 

9.4.4 Stream Formatting 9-5 

9.4.5 I/O Buffering & Sector Interleaving 9-5 

9.4.6 Retension Pass 9-6 

9.5 Formatting 9-6 

9.5.1 Format Description 9-6 

9.5.2 Data Integrity 9-9 

9.5.3 Format Operation 9-9 

9.6 Access Timing 9-12 

9.6.1 Stream To Stream 9-12 

9.6.2 Segment To Segment 9-12 

9.6.3 Read Reposition 9-14 



li 



TABLE OF CONTENTS (Continued) 



APPENDIX A CONFIGURATION TABLES A-l 

A.l Jumper Options A-l 

A.2 Stream Selection Tables A-l 

A.3 Service Aids A-4 

A.3.1 Continuous Forward /Reverse A-4 

A.3.2 Stream Positioning - All Streams A-4 

A.3.3 Stream Positioning - Streams & 4 A-4 

A.3.4 Cyclic Tape Motion A-4 

APPENDIX B OPERATING PARAMETER CONSIDERATIONS B-l 

B. 1 Time Outs B-l 

B.2 Read After Write B-l 

B.3 Re instruct Timing B-2 

B.4 Sec tors /Segment Counts B-2 

B.5 Stream (Drive) Selection B-2 



111 



LIST OF ILLUSTRATIONS 



Figure Page 

1-1 525 Floppy Tape Drive 1-1 

1-2 The Evolution of Floppy Tape 1-2 

3-1 525 Functional Block Diagram 3-2 

3-2 Component Location Layout 3-3 

3-3 Read/Write Head Assembly 3-3 

4-1 525 Physical Tape Layout 4-1 

4-2 525 Stream Partitioning Layout 4-2 

4-3 Stream Access Flowchart 4-3 

4-4 Random Segment Access Timing 4-4 

4-5 Read Timing 4-5 

4-6 Write Timing 4-6 

5-1 525 Drive Interface - SA450 5-1 

5-2 525 Drive Interface - SA850 5-2 

5-3 I/O Listing 5-3 

5-4 Interface Signal Driver/Receiver 5-4 

5-5 Read Data Signal - FM & MFM 5-6 

5-6 Write Data Signal - FM <5c MFM 5-7 

6-1 525 Interface Connectors - SA450 6-1 

6-2 J 1 Interface Connector Dimensions - SA450 6-1 

6-3 Jl Interface Connector Dimensions - SA850 6-2 

7-1 525 Dimensions 7-1 

9-1 Typical Host System (Block Diagram) 9-1 

9-2 Typical Floppy Disk Host Controller 9-2 

9-3 525 Controller Example - SA450 9-3 

9-4 FM vs. MFM Recording 9-5 

9-5 IBM System 34 Format Example 9-8 

9-6 Format Flowchart 9-10 

9-7 Verification Pass Flowchart 9-10 

9-8 Stream Format Timing 9-1 1 

9-9 Head Positioning 9-12 

9-10 Contiguous Segment-to -Segment Timing 9-13 

9-1 1 Read Reposition Timing 9-14 



IV 



SECTION 1 
INTRODUCTION 



1.1 



SCOPE 



This manual describes the electrical and 
mechanical characteristics oL Cipher Data 
Products' 525 FloppyTape M 1/4-inch 
cartridge tape drive. It contains the 
timing, electrical, and mechanical 
specifications for the 525, which is 
available with a data rate of 500 KHz with 
SA450 or SA850 interface, or a 250 KHz 
rate with a SA450 interface. It also 
recommends the formats and circuitry 
necessary to interface the 525 to a host 
controller. 

The information in this manual is correct at 
the time of publication, but is subject to 
change without notice. This information is 
the exclusive property of Cipher Data 
Products, Inc. and shall not be reproduced 
in any manner without the written 
permission of Cipher Data Products, Inc. 




1.2 



TERMINOLOGY 



The following new or, possibly, unfamiliar 
terms relate to FloppyTape technology: 



Figure 1-1. 525 FloppyTape Drive 



o Sector - smallest unit of addressable memory located within a segment. 

o Segment - a fixed length of tape that emulates a floppy disk track. Each segment is 
26.55 inches, and has the capacity (unformatted) of 20.5 kilobytes. See Figure 1-2. 

o Stream - one of six physical bit serial tracks recorded on tape. Each stream 
contains 255 segments (0-254). See Figure 1-2. 

o Index Pulse - a signal sent to the host controller by the 525 to indicate the detection 
of an Index Mark. An Index pulse can be used by the host controller to initialize 
segment operations. 

o Index Mark - a portion of a stream in which the oxide is saturated in one direction. 
An Index Mark is used for the logical separation of segments. See Figure 1-2. 

o Upstream - a position on tape that is between the present location and the logical 
End of Stream (EOS). See Figure 1-2. 

o Downstream - a position on tape that is between the present location and the logical 
Beginning of Stream (BOS). See Figure 1-2. 

o Host Controller - the hardware required to interface the 525 to the host computer. 



1-1 



INDEX MARKS 

T 




TRKO 



•Tracks 
Track 5 

■Track 4 
Track 3 
Track 2 
Track 1 

■ Track 



TRKO 



Becomes 26.55" of Tape Recorded at 6400 BPI 




255 Segments become a Stream 



O O O 



O O O 



O-*- 



n i 4 A 

18" 18" 18" 



^T 



STREAM 1 
STREAM 2 
STREAM 3 
STREAM 4 
STREAM 5 
STREAM 6 



o o o 



1/4" 



LOAD 
POINT 



PHYSICAL 

BEGINNING 

OF TAPE 



DATA AREA 600' 



I 48 
EARLY 
WARNING 
HOLE 



4 4 4 il 
18" 18" 18 



PHYSICAL END 
OF TAPE 



Figure 1-2. The Evolution of FloppyTape 



1-2 



1.3 GENERAL DESCRIPTION 

The Cipher 525 Floppy Tape cartridge tape drive is a low cost, computer data storage 
tape drive, employing the 3M DC600A or any other Cipher approved 1/4-inch cartridge 
tape media. The 525 emulates the industry standard SA850 or SA450 interface and 
responds to common floppy disk drive commands. Emulation of a floppy disk drive is 
accomplished by the Floppy Tape's on-board Z8603 microprocessor. Data is recorded in a 
bit serial manner on each one of the six streams on the tape. Streams are selected by 
the host system via the four Drive Select and Side Select lines supported by the standard 
SA850 or SA450 bus. The host treats each stream as a logical disk surface. Prior to any 
stream access, the host system must select one of the six logical surfaces. Actual 
physical stream selection is accomplished by first having the Z8603 microprocessor 
interpret the Drive Select and Side Select lines, then positioning the Read/Write head on 
the selected stream. Each stream has an unformatted capacity of 5.2 megabytes. 

Emulation of a floppy disk track is achieved by partitioning a stream into 26-inch 
segments. Segments are separated by DC saturated portions of tape referred to as Index 
Marks (IMs). Stream partitioning into segments by IMs is done by the Z8603 
microprocessor during a stream format operation initiated by the host system. Following 
the format operation, the Floppy Tape uses the IMs to generate the Index Pulse signal 
seen by the host on the interface. IMs are also used by the Floppy Tape to count the 26- 
inch increments of tape, when a segment seek operation is initiated by the host system 
controller. The unformatted capacity of a segment is 20.5 Kbytes (approximately twice 
the capacity of an 8-inch floppy disk track). Segments are accessed by the host system 
using the floppy disk protocol step and direction lines from the floppy disk controller. 

1.4 FEATURES 

The main features of the 525 Floppy Tape include: 

o Standard ANSI cartridge mounting 

o Precise head stepping 

o SA450 or SA850 floppy disk interfaces 

o Operable with existing floppy disk controller chips 

o No AC requirements 

o 5-1/4-inch form factor 

o High capacity storage (32 MB) 

o Soft sector type floppy disk format 

o Enclosed/removable media 

o Low maintenance 



1-3 



SECTION 2 
SPECIFICATIONS & RELIABILITY 



2. 1 TAPE SPECIFICATIONS 

Tape Speed/Transfer Rate:* 

Ramp Time: 

Tape Speed Variation 
Low Frequency: 
Instantaneous: 

Write Pre-compensation: 

MFM Recording Density: 

Unformatted Capacity (MFM Recording) 
Segment: 
Stream: 
Cartridge: 

Recording Tracks: 

Recording Method: 

Interface Code 

Recommended: 
Available: 



78 ips/500 Kbits/sec 

or 

39 ips/250 Kbits/sec 

350 ms 



Less than ±2% 
Less than ±6% 

200 ns @ 500 Kbits/sec 
250 ns @ 250 Kbits/sec 

6,400 bpi nominal 



26.55 inches = 20.5 Kbytes max. 
255 segments = 5.2 Mbytes 
6 streams = 31.3 Mbytes 

6 

NRZ 



Modified Frequency Modulation (MFM) 
Frequency Modulation (FM) 



2. 1 . 1 Recording Times 

78 ips (500 Kbits/sec) 

39 ips (250 Kbits/sec) 

2.1.2 Positioning 

Method: 
^Transfer rate is tape drive dependent. 



0.333 sec/segment 
93 sec/stream 
558 sec/cartridge 

0.666 sec/segment 
186 sec/stream 
1,116 sec/cartridge 



Multi-position stepper motor 



2-1 



2.2 RELIABILITY 

2.2.1 Mean Time Between Failures (MTBF) 

The MTBF for a drive is defined as follows: 



MTBF 



Power-on Hours 



Number of Equipment Failures 



Definitions 



Failures caused by operator error, or an out-of-specification operation, are not counted 
as failures. 

Product Workload is stated in terms of a unit duty cycle, and is defined as actual tape 
motion time divided by total power-on time. 

Infant mortality failures which occur within the first 100 hours of power-on time after 
site installation are not considered in the MTBF calculations. 

The sample size must be greater than 100 units for the purpose of MTBF calculation. 

Production and design maturity improvements allow the MTBF rate to be achieved 18 
months from start of production. In the interim the actual MTBF might be lower. The 
minimum MTBF for the 525 is: 



Product Workload 


MTBF (Hours) 


20% 


19,250 


40% 


9,625 


60% 


6,416 


80% 


4,813 



2.2.2 Mean Time To Repair (MTTR) 

MTTR is defined as the time for an adequately trained and competent serviceman to 
diagnose and correct a malfunction at the subassembly level. 

The MTTR is expected to be 15 minutes. 

2.2.3 Preventive Maintenance (PM) 

The 525 requires no service call related PM. The hours of required operator PM are 
related to the product workload. 



2-2 



Product Workload 


Hours of PM/100 Hours On 


20% 


0.1 


40% 


0.3 


60% 


0.4 


80% 


0.4 



This preventive maintenance, at a minimum, involves cleaning the tape path, including 
the recording head and the drive roller surface. 



2.3 



DATA INTEGRITY 



Errors attributed to operator mishandling of the tape cartridge, or errors on the 
cartridge which can be detected and flagged during formatting, are not included in 
determining error rates. 



2.3.1 



Media 



Only cartridges from Cipher approved sources may be used, such as the 3M DC600A. 
Properly handled, the cartridge can be used for at least 5,000 full length passes. (BOT to 
EOT and back to BOT is considered 2 passes.) 



2.3.2 



Recoverable Read Errors 



A recoverable error (soft error) is one which may be corrected by no more than 10 re- 
read attempts. Data patterns, tape position, and Read/Write head position do not affect 
data error rate performance. 

The recoverable read error rate for the 525 is less than I in 10 bits. 

2.3.3 Non-Recoverable Read Errors 

A non-recoverable read error (hard error) is one which cannot be corrected by JO re-read 
attempts. The non-recoverable read error rate for the 525 is less than I in 10 bits. 

2.3.4 Power Loss 

Accidental loss of DC power will not result in any component failure. 



2-3 



SECTION 3 
FUNCTIONAL CHARACTERISTICS 

3.1 GENERAL DESCRIPTION 

The 525 Floppy Tape 1/4-inch cartridge tape drive consists of Read/Write electronics, 
control logic, tape drive mechanism, head positioning mechanism, and the Read/Write 
head. These components perform the following functions: 

o Interpret, generate, and emulate floppy disk drive control signals 

o Position the Read/Write head on the logically selected stream 

o Monitor and control tape speed 

o Read and Write data 

Figure 3-1 is a block diagram of the 525 Floppy Tape. The host system interfaces the 525 
through the control and data signal bus. The control signals are interpreted, and 
appropriate action is initiated by the tape motion control logic. 

Tape is transported across the Read/Write head in both directions by a direct-drive DC 
capstan motor. The built-in tachometer circuit provides feedback to the control 
electronics for constant motor speed adjustment. 

A photo detector senses the Beginning Of Tape (BOT), the Early Warning (EW), and the 
End Of Tape (EOT) holes. The on-board microprocessor initiates subsequent control 
actions. 

The Write protect circuitry guards against accidental alterations of recorded data 
inhibiting the Write electronics when the cartridge tumbler is in the "safe" position. 

Figure 3-2 shows the physical locations of these components on the 525 chassis. 

3.2 READ/WRITE & CONTROL ELECTRONICS 

The Read/Write and control electronics are located on a single Printed Circuit Board 
(PCB). The PCB components include the following circuits: 

o Index Detector/Generator 

o Write Current Driver 

o Read Amplifier and Transition Detector 

o Write Protect Logic 

o Logical Drive/Stream Selection 

o Tape Speed /Capstan Control 

o Tape Hole Monitor 

3-1 



READ DATA 



WRITE DATA 



WRITE GATE 



WRITE PROTECT 



STEP 



DIRECTION 



TRK00 



INDEX 



MOTOR ON 



READY 




READ 
AMP 



WRITE 
LOGIC 



I 



CONTROL 
LOGIC 



INDEX 
DETECT 



-►<> 

I 



MTR 
DRV 



n a 



ENABLE 



DIRECTION n 



HI SPEED 



LTH 



UTH 



!► HEAD 




CAPSTAN 



EOT- BOT 
SENSOR 




n 



HEAD 
POSITION! 



Figure 3-1. 525 Functional Block Diagram 



3-2 



CAPSTAN 



CARRIAGE 



READ/WRITE 
HEAD 




TAPE HOLE 
MONITOR 



WRITE PROTECT/ 
CARTRIDGE IN 
SWITCHES 



3.3 



Figure 3-2. Component Location Layout 
TAPE DRIVE MECHANISM 



The tape drive capstan is driven by a three-phase, brushless DC motor. Feedback from 
the integral tachometer is utilized by the on-board microprocessor for accurate pulse- 
width modulation speed control. 

Precise cartridge-to-head alignment is accomplished with a "floating" cartridge carriage 
assembly. Forces applied, similar to those recommended by ANSI 3.55-1977, locate the 
cartridge positively against the three registration pins and the datum surfaces of the 
deck plate. This configuration assures exact media positioning. A sliding contact pin 
opens the tape cartridge door to enable contact between the media and Read/Write head. 



3A 



READ/WRITE HEAD POSITIONING MECHANISM 



The Read/Write head is positively locked 
against the media by an upward turn of the 
cartridge lock lever. Stream access is 
performed by a multi-position four-phase 
head stepper motor. The head stepper 
motor is driven by the control logic in 
response to Drive/Side Select signals 
received from the host controller. 

The stepper mechanism provides an 
approximate step size of one mil (0.001 
inch) to position the head. 

The 525 is designed with a single element, 
glass-bonded ferrite/ceramic head with 
tunnel erase. 




STEPPER MOTOR 
LEAD SCREW 



CYLINDER 

GRAPHITE 
PISTON 



READ/WRITE HEAD 



Figure 3-3. Read/Write Head Assembly 



3-3 



SECTION 4 
FUNCTIONAL DESCRIPTION 



<U 



POWER SEQUENCING 



The DC voltage (+5V, +12V) can be applied in any sequence. However, in order to 
maintain data integrity during power-up, the Write Gate line must be held inactive, or 
the cartridge lock lever must be in the open position. On a power-up sequence, or the 
insertion of a new cartridge, the drive automatically performs a retension pass of the 
tape, leaving the medium positioned at Stream 1, Segment 0. (See Paragraph, 9.4.6) 



*.2 



STREAM SELECTION 



Stream selection occurs as a function of the Drive and Side Select lines. These lines are 
used as inputs to a decode PROM. Through the use of three jumpers (Wl, W2, W3), a 
total of seven possible stream configurations can be derived. (See Stream Selection 
Tables, Appendix A.) 

When a new stream is selected and the Head Load or Motor On line asserted, the tape 
automatically moves to Segment of that stream. If no Step pulses are received, the 
tape will position on the new stream at the same segment number as on the previous 
stream. Each time a new stream is selected, it is recommended that the host issue a 
recalibrate command to its controller to avoid tape device/controller confusion. (See 
Figures 4-1 and 4-2.) 



o o o 



o o o 



o-*- 



STREAM 1 
STREAM 2 
STREAM 3 
STREAM 4 
STREAM 5 
STREAM 6 



1/4" 



o o o 



I" 18" 18' 



TT 



48" 



LOAD 
POINT 



PHYSICAL 

BEGINNING 

OF TAPE 



| 48' 

EARLY 

WARNING 

HOLE 



DATA AREA 600' 



PHYSICAL END 
OF TAPE 



Figure 4-1. 525 Physical Tape Layout 



4-1 



STREAM 




INDEX MARK 

(DC ERASED 

AREA OF 

TAPE) 



• SEGMENT- 



A LENGTH OF TAPE WHOSE 
BIT CELL CAPACITY IS 
20.5 K BYTES 



SECTOR" 



SECTOR* 



SECTOR* 



SECTOR' 



SECTOR' 



4.3 



NOTE" THE SOFT SECTORING OF A SEGMENT 

IS A FUNCTION OF THE HOST CONTROLLER 

Figure 4-2. 525 Stream Partitioning Layout 
HEAD LOAD/MOTOR ON 



The Head Load line on the SA850 interface serves the same purpose as the Motor On line 
on the SA450 interface. This line must be asserted in order to Write or Read data. 
Following the assertion of the Head Load/Motor On line, a 400 ms nominal delay is 
introduced prior to any data operation to allow the medium to reach full operating speed. 

If the Head Load/Motor On line is asserted and no Step pulses are issued by the host, the 
525 always repositions to the last accessed segment. If, after four seconds, accessing has 
still not occurred, the host should deactivate the Head Load/Motor On line to avoid 
excessive wear of the medium. 



4.4 



SEGMENT ACCESSING 



Segment accessing requires the host controller to perform the following steps: 

a. Select the desired stream 

b. Activate the Head Load/Motor On line 

c. Read the segment /sec tor address mark from the tape 

d. Compare the segment /sec tor address read from the tape to the target 
segment/sector address. If there is a mismatch, go to Step e. Otherwise go to 
Step f. 

e. Address mismatch: determine the direction of the target segment within the 
stream and activate the Direction line accordingly. Issue Step pulses equal to 
the offset difference between the actual and the target address. 

With the Head Load/Motor On line still asserted and with an incoming stream 
of Step pulses, the 525 responds by moving the tape in the direction selected 
by the Direction line until the number of Index Marks passed is equal to the 
number of Step pulses received. At this point, the host should reenter this 
procedure at Step c. This process is repeated until a segment address mark 
compare occurs. (See Figure 4-3.) 

f. Address match: access the appropriate sector within the segment. 



4-2 



( ENTER J 



SELECT 
DESIRED 
STREAM 



ACTIVATE 
HEAD LOAD / 
MOTOR ON 



READ 
ADDRESS MARK 
FROM TAPE 



SET 
DIRECTION LINE 



ISSUE 
STEP PULSE 




YES 



HOST CONTINUES 
OPERATION 



Figure 4-3. Stream Access Flowchart 



4-3 



4.5 



STEP OUT/STEP IN 



The Direction Select line is used to send a pulse which moves the tape to the next 
segment (step out), or the previous segment (step in). 

Step Out 

With the Direction Select line at a high logic level (+2.5V to +5. 25V), a pulse on the Step 
line, in conjunction with Head Load or Motor On, moves the tape downstream to the next 
segment. 

Step In 

With the Direction Select line at a low logic level (0,0V to +0.8 V), a pulse on the Step line 
in conjunction with the Head Load or Motor On, moves the tape upstream to the next 
segment. See Figure 4-4. 



DC POWER 



J 



DRIVE/SIDE SELECT 



READY 



HEAD LOAD / 
MOTOR ON 



INDEX 



STEP 



DIRECTION 



READ DATA 



X 



VALID STREAM SELECTION 



\^- 160SECMAX(AUTO RETENSION) 



1 ms MIN 



SEE NOTE *-U 

1 (*sec MIN ->-\ j-*- J 

=u — u 



X 



100 Msec 
MIN 



TARGET SEGMENT DATA 



NOTE: Time to target segment is approximately equal to the number of Step pulses 
issued times 333 ms. 

Figure 4-4. Random Segment Access Timing 

4.6 READ OPERATION 

Reading data from the 525 drive is accomplished by: 

a. Activating Drive Select to select the desired stream 

b. Activating the Head Load/Motor On line 

c. Deactivating the Write Gate line 
Timing relationships are shown in Figure 4-5. 



4-4 



DC POWER i 


DRIVE/SIDE SELECT } 


^^ — VALID STREAM SELECTION 










SEC MAX(AUTO RETENSION) 




— wl 




-<- 160 




AEADY j 


















HEAD LOAD/ 1 
MOTOR ON 2 










-H 




|«^- 400 ms NOM 




INDEX J 




1 


< 333 ms -^J 




STEP 






-^j j^- 1 fisecMIN 

— *H H*~ 1 ,*secMIN 




DIRECTION . 








I 








1 




READ DATA j~ 


SEGMENT N DATA — 


*4HII 


lllllllllll 


mi *]iiiiiiiiiiin 


iiiiiiii 



NOTES: 1. Timing is measured at the host. 

2. If no Step pulse is received, the 525 will not issue the second Index pulse 
until the unit completes repositioning on the same segment. 

Figure 4-5. Read Timing 

4.7 WRITE OPERATION 

To Write data on the 525, the following steps are performed: 

a. Activate the Drive Select 

b. Activate the Head Load/Motor On line 

c. Activate the Write Gate line 

d. Pulse the Write Data line with the data to be written. The Write timing 
relationships are shown in Figure 4-6. 



4-5 



DC POWER 



_r 



DRIVE/SIDE SELECT 



REAflV 



HEAD LOAD/ 
MOTOR ON 



INDEX 

STEP 
DIRECTION 

READ 6 At A' 

WRITE GATE 
WRITE DATA 



X 



VALID STREAM SELECTION 



160 SEC MAX (AUTO RETENSION) 



—4*\ |-*» 400 ms NOM 

II 



-<333ms 






1 usee MIN 
1 »sec MIN 



SEGMENT N DATA- 



-Hlllllllll lllllll -illlllllllllllllllllll 

^ SEGMENT N+1 DATA 



-**j 1^- 4 Msec MAX 



EDIT DATA -^j|[|| 



NOTES: 1. Timing is measured at the host. 

2. If no Step pulse is received, the 525 will not issue the second Index pulse 
until the unit completes repositioning on the same segment. 



4.8 



Figure 4-6. Write Timing 
RECORDING FORMAT 



The data format recorded on the cartridge tape is a function of the host system. The 
format should be designed around the user's application to take maximum advantage of 
the available storage capacity. 

For detailed recording format information, refer to Section 9 and Appendix B. 



4-6 



SECTION 5 
INTERFACE SIGNALS 



5.1 



DRIVE INTERFACE 



The 525 requires two separate connections to the host controller: 31, the digital signal 
interface which provides control signals and data and 32 which provides DC power. 
Connector dimensions are detailed in Section 6. 



HOST CONTROLLER 



FLAT RIBBON OR 
TWISTED PAIR 

MAX 10 FEET 



DCGND 



////// 

ACGNO 



READY 



DRIVE SELECT 4 



INDEX 



DRIVE SELECT 1 



DRIVE SELECT 2 



DRIVE SELECT 3 



MOTOR ON 



DIRECTION SELECT 



STEP 



WRITE DATA 



WRITE GATE 



TRACK 00 



WRITE PROTECT 



READ DATA 



SIDE SELECT 



+5 VDC 



+5 RETURN 



+ 12 VDC 



+12 RETURN 



%- 



TWISTEDPAIR 



10 



12 



16 



18 



20 



22 



24 



26 



28 



30 



/77777 

FRAME GND 



NOTE: ALL ODD NUMBERED PINS ARE GROUND 



Figure 5-1. 525 Drive Interface - SA450 



525 




5-1 



FLAT RIBBON OR 
TWISTED PAIR 



NOTE: ALU ODD NUMBERED PINS ARE GROUND 



Figure 5-2. 525 Drive Interface - SA850 



HOST CONTROLLER 






MAX 10 FEET 


525 










J1 












/ 








< 
< 




SIDE SELECT 






S 








HEAD LOAD 


1R 




s 












INDEX 






20 y - 








READY 






22 y 








DRIVE SELECT 1 














DRIVE SELECT 2 _ 






y 








DRIVE SELECT 3 _ 






30 y 








DRIVE SELECT 4 _ 






3. ^ 








DIRECTION SELECT 






21 / 








STEP 


36 _^— ■ 












WRITE DATA 


38 > 










WRITE GATE 


40 y 










_ TRACK 00 






4. ^ 








_ WRITE PROTECT 


44 y 














READ DATA 


46 

J2 


^ +5 VDC _ 




X 


+5 RETURN 


/ 






DC GND « 
S777 

AC G 




X +12VDC _ 






X 


+12 RETURN 


X 












- 


ND 




£ 


= TWISTEDPAIR 


////// 

FRAME GND 







5-2 



SA850 


SA*50 










Pin# 


Pin// 


Name 


I/O 


Signal 


Description 


Input Control Signals 


26 


10 


DS 1 


I 


Drive Select 1 


Stream selection with Side Select 


28 


12 


DS2 


I 


Drive Select 2 


Stream selection with Side Select 


30 


14 


DS3 


I 


Drive Select 3 


Stream selection with Side Select 


32 


6 


DS4 


I 


Drive Select 4 


Stream selection with Side Select 


14 


32 


SS 


I 


Side Select 


Stream selection 



34 18 


DIRC 


I 


Direction Select 


When low (true), in conjunction 
with Step pulse, causes tape to 
move toward Segment 254 of 
selected stream 


36 20 


STP 


I 


Step 


When pulsed causes tape to move 
one segment per pulse in the 
direction selected by the 
Direction line 


!8 


HLD 


I 


Head Load 


Causes tape motion 


16 


MTON 


I 


Motor On 


Causes tape motion 


40 24 


WGT 


I 


Write Gate 


Enables writing of data 


Output Control Signals 


20 8 


INDX 





Index Pulse 


Indicates beginning of a segment 


42 26 


TRK00 





Track 


Indicates tape position is at, or 
going to, Segment of selected 
stream 


44 28 


WPT 





Write Protect 


When low, indicates cartridge is 
Write protected 


22 2 


RDY 





Ready 


Indicates cartridge in, retension 
pass done 


Data Line Signals 


38 22 


WD 


I 


Write Data 


Data to be written 


46 30 


RD 





Read Data 


Read data from tape 



Figure 5-3. I/O Listing 



5-3 



5.2 INTERFACE SIGNAL LEVELS 

True = Logical = V jn ±0.0 to +0.8V 

@ I in = 40 ma (max) 

False = Logical 1 = V in +2.5V to 5.25V 

@ I ipi = ma 
^ in 

Input Impedance =150 ohms 

7438 I 



HOST 



t=3 



7414 



o 



150 



5V 



525 



150 

Q 



7414 



i> 



7438 




Figure 5-4. Interface Signal Driver/Receiver 
53 INPUT CONTROL SIGNALS 

Drive Select 

The four Drive Select lines (DS1 - DS4), used with the Side Select (SS) line, and 
the configuration jumpers WI, W2, W3, allow selection of one of six logical 
drives. When a particular drive is selected, the head moves to the appropriate 
stream and the microprocessor is enabled to scan and respond to other control 
signals. 

Head Load/Motor On 



When the Head Load (HLD) or Motor On (MTON) line, and Drive Select (DS) 
lines are asserted by the host controller, the capstan on the selected drive is 
enabled and tape motion begins. 

Direction Select 



The Direction Select (DIRC) line is used by the 525 to control the direction of 
tape movement. If this line is low, it causes the tape to move upstream. If it 
is high, it causes the tape to move downstream. 



5-4 



Step 

A pulse on the Step line (STP) causes the tape t o mov e one segment from its 
current position in the direction controlled by the DIRC line. 



DIRC = I Tape motion towards logical Segment 0. 
DlRC = Tape motion towards logical Segment 254. 



Write Gate 



The Write Gate (WGT) line allows the host to disable the Step function and 
enable the Write drivers. A false (high) level on this line enables the Read 
output to the Read amplifier section so data may be read. 

5.4 OUTPUT CONTROL SIGNALS 

Track flfl 

A logic low level on the Track line (TRJ5&) indicates the 525 is at, or going to, 
the first segment (00) of the selected stream. 

Index 



A pulse on the Index (INDX) line indicates that the drive is at the beginning of 
a segment in the selected stream. The segment time from Index Mark to Index 
Mark in a write format routine is 333 milliseconds. 

Write Protect Signal 



A low on the Write Protect (WPT) line indicates that the safe tumbler on the 
cartridge has been manually set. The 525 Write circuits are also disabled under 
this condition. 



5-5 



5.5 DATA LINE SIGNALS 

5.5.1 Read Data Signal 

While reading, this line provides a 300 ns pulse for each flux transition detected on the 
tape. 

FM Recording 



READ DATA" 
FM 



„ 300 ns 

±50 ns 

ru 


BIT CELL 

« 4 /* s ■ » 
NOM 


2 ms 
NOM 


LI 



I i 

C D 



2 ms 

NOM 



C = Clock Pulse = 300 +100 ns 
Bit Cell Time = 4 /us 



D = Data Pulse = 300 ±50 ns 



MFM Recording 



READ DATA 
MFM 



Figure 5-5. Read Data Signal - FM Recording 




D = Data Pulse = 300 +50 ns 
Bit Cell Time = 2 /js 



Figure 5-5. Read Data Signal - FM & MFM 



5-6 



5.5.2 Write Data Signal 

The Write Data line (WD) supplies data from the host controller to the Read/Write 
head. Each transition from a one to a zero on this line causes a reversal of the Write 
current direction through the Read/Write head. The Write Data line is enabled by the 
Write Gate control line. 

FM Recording 



WRITE DATA' 
FM 



LTU 



150 ns MIN 
1000 ns MAX 



4.00 ps±20 ns 
BIT CELL 



Lf 



2.00 ia 
±10 ns 



C - Clock Pulse = 150 ns min, 1 us max. 
D = Data Pulse = 150 ns min, 1 us max. 
Bit Cell Time = 4 jis +20 ns 



MFM Recording 



WRITE DATA 
MFM 



1 MS 
±10ns 



-i C »- 

2*is — >■ 



i C * 



*— C 



1 



mm! mJ 



u 



D = Data Pulse = 150 ns min, 1 u.s max. 
Bit Cell Time = 2 us +10 ns 



Figure 5-6. Write Data Signal - FM & MFM 



5-7 



SECTION 6 
PHYSICAL INTERFACE CONNECTION 



6.1 



INTERFACE CONNECTOR LOCATIONS 



Control and data signals are transferred between the host controller and the 525 via 
connector Jl. 31 is a 50-pin connector on the SA850 interface unit, and a 34-pin 
connector on the SM50 interface drive. J2 is a 4-pin connector used to supply DC 
power. 



® 




ji 



2 6 



34 



II UIIIIIIIIIIHII 



\ 



KEY SLOT 



© 



Figure 6-1. 525 Interface Connectors - SA450 



6.2 



SIGNAL CONNECTOR DIMENSIONS 



KEY SLOT 



.400 t .010" 



2 -, 



.036 ±.004" 



.450 ± .010" 



.050" NOM 

•4 .050" NOM .100" NOM 

1.795 ± .005 ' 




«« .063" NOM (2X) 



BOARD THICKNESS .062 ± .007 



Figure 6-2. Jl Interface Connector Dimensions - SA450 



6-1 



KEY SLOT 



036 ±.004" 




450 ± .010" 



.050" NOM 
050" NOM .100" NOM- 

2.575 ±.010- 



50 



.063" NOM (2X) 



6.3 



BOARD THICKNESS .062 ± .007 

Figure 6-3. Jl Interface Connector Dimensions - SA850 
RECOMMENDED CABLES AND CONNECTORS 



The control/ data signal interface cable may be a twisted pair or a flat ribbon cable. The 
maximum cable length is ten feet. Minimum conductor size is 26 AWG. The following 
table provides recommended mating connector information. 



Cable Type 


34-Pin/SA450 Interface 


50-Pin/SA850 Interface 


Twisted Pair 


AMP #583717-5 with 


AMP#1 - 583717-1 with 




AMP # 1-5836 16-i crimp pins 


AMf in- ;>5j)bibo crimp pins or 
AMP #1 - 583854-3 solder pins 

Also 
Viking #3VH35 with 
Viking #DN-5 solder lugs 


Flat Ribbon 


3M // 3463-0001 


3M #3415-001 



The mating DC connector is a 4-pin AMP MATE-N-LOCK, AMP P/N 1-480424-0 with 
AMP pins P/N 61473-2. 

Minimum conductor size for interconnect wires is 18 AWG. 

6.4 TERMINATION 

The 525 terminates all signal lines with 150 Ohms to +5V. 

Terminators for Head Load/Motor On, Direction, Step, Side Select, Write Gate, and 
Write Data consist of one SIP package network. This resistor pack should be removed if 
the 525 is not the last drive on the bus in a daisy chain configuration with floppy disk 
drives. 



6.5 



FRAME GROUND 



In order to reduce noise susceptibility, the 525 drive frame should be grounded to the AC 
or frame ground of the host controller. If the frame of the drive is not fastened directly 
to the frame of the host system, a wire must be connected from the 525 drive frame to 
ground. 



6-2 



SECTION 7 
PHYSICAL CHARACTERISTICS 



7.1 



MECHANICAL DIMENSIONS 



Width: 


5.75 in. (146 mm) 


Height: 


3.25 in. (83 mm) 


Depth: 


8.00 in. (203 mm) 


7.2 


WEIGHT 


Unit Weight: 4.0 lbs. (1.8 kg) 


Shipping 


Weight: 7.0 lbs. (3.2 kg) 



The 525 can be mounted in the same space as a 5-1/4-inch floppy disk drive. The unit 
may be mounted horizontally or vertically. In the horizontal position, the PCB must be 
on top. In the vertical position, the PCB board should be on the right side while viewing 
the unit from the front. 

CAUTION: Do not mount the 525 upright (cartridge slot facing up). 

Four base holes and two holes on each side are provided for mounting. The holes are 
tapped for 6-32 screws. See Figure 7.1 for mounting hole locations. Screws used for 
mounting must penetrate the mounting surface by at least 0.125 inches (3.2 mm), but no 
more than 0.22 inches (5.6 mm). The mounting surface thickness is 0.047 inches (1.2 mm). 



H 



o 



M 



PWB 
COMPONENT SIDE 




- 3.12 * .02 
2 PLACES 



.08 ± .01, TYP. 



_L 



8-32 NC-2B = 20 OP 

MAX MOUNTING HOLES, 

8 PLACES 



Figure 7-1. 525 Dimensions 



U. ■. 



7-1 



8.1 



8.2 



8.3 



8.4 



8.5 



SECTION 8 
ENVIRONMENTAL CHARACTERISTICS/POWER REQUIREMENTS 



TEMPERATURE 

Operational: 

Non-Operational: 
Temperature Cycling: 
HUMIDITY 

Operational: 

Non-Operational: 

ALTITUDE 

Operational: 

Non-Operational: 

Shipping: 

VIBRATION 

Equipment 
Operational: 



Equipment 
Non-Operational: 



SHOCK 



5 to 45°C, measured at cartridge base 
(max. gradient of 1°C per minute) 

-30 to 60°C 

No condensation shall result 



20 to 80% relative humidity* 

1 to 90% relative humidity* 

*Wet bulb temperature 26° max., non-condensing 

Sea level to 10,000 ft (3,000 m) 

Same as Operational 

Sea level to 49,000 ft (15,000 m) 



The unit shall withstand a peak acceleration of 
0.3g for the frequency range of 5-500 Hz along 
each orthogonal axis. 

The unit shall withstand a peak acceleration of 
0.3g for the frequency range of 5-500 Hz along 
each orthogonal axis. 



The equipment in a non-operational status shall not suffer damage or fail to operate 
according to specifications, when subjected to a 30g shock. 



8.6 



AIR QUALITY 



The unit will function in a normal office environment, i.e., up to 60 milligrams of 
5-micron diameter dust particles per 100 cubic feet of air. 



8-1 



8.7 ACOUSTICAL NOISE 

Standby: Inaudible 

Steady Tape Motion: Less than 55 dba at a distance of 3.3 feet (1 m) 

8.8 DC POWER 

+5V ±5%, 0.8A max., 50 mV max. ripple (peak to peak) 

+12V ±5%, 1.8A nominal, 2.5A surge max. during cartridge acceleration (350 ms 
duration). 100 mV max. ripple (peak to peak). 

Source Impedance: 50 milliohms max. 

<8.9 HEAT DISSIPATION 

25.6 Watts operational: 87 BTU/hr 

35.0 Watts surge (250 ms duration): 119 BTU/hr 

8.10 COOLING 

Dependent on individual mounting and type of operation, 15 cf/min fan recommended for 
most applications. 



8-2 



SECTION 9 
APPLICATION NOTES 



9.1 



GENERAL 



This Section addresses hardware and software considerations for integrating the 525 into 
a host computer system. The information supplied is based on formatter designs utilizing 
controller chips as outlined in Appendix B. 



HOST CPU 




GLOBAL BUS 



Figure 9-1. Typical Host System (Block Diagram) 



9-1 



9.2 



HARDWARE CONSIDERATIONS 



The mounting, interfacing, and operation of the 525 emulates a standard floppy disk 
drive. Figure 9-2 illustrates the interfacing of a 525 to a typical host controller. Figure 
9-3 is an example of a controller interface schematic for the 525. 



HOST 
INTERFACE 



ADDRESS/CONTROL 
BUS 



> 



CONTROLLER 
SELECT 
LOGIC 



IMPLEMENTED 

IN FLOPPY DISK CONTROLLER 



COMMAND 
PROCESSOR 



T\ 



DRIVE 
SELECT 
LOGIC 




COMMAND/DATA 



TRACK 

POSITIONING 

LOGIC 



to 



CAPSTAN 

CONTROL 

LOGIC 




READ/ 
WRITE 
LOGIC 



DRIVE 
INTERFACE 



DS1 



DS3 



DS4 



DIRC 



TRK00 



MTON 



WPT 



INOX 



RD 



WGT 



WD 



Figure 9-2. Typical Floppy Disk Host Controller 



9-2 



WD 2793 



DRIVE INTERFACE 
<T| READY 
^>— -f2T> WRITE GATE 
■T2T> WRITE DATA 



CONTROL 
SIGNALS 



I 




WRITE PRECOMP 
ENABLE JUMPERS 






DRIVE SELECT 1 



DRIVE SELECT 2 



DRIVE SELECT 3 



LOAD SELECT > 
REGISTER 



{jP> DRIVE SELECT 4 



Figure 9-3. 525 Controller Example - SA450 



9.3 ENCODING TECHNIQUES 

The recording format on the tape cartridge is strictly a function of the host system. 
Data may be recorded, using either Frequency Modulation (FM) or Modified Frequency 
Modulation (MFM) encoding. MFM encoding is recommended, due to its more efficient 
utilization of tape storage capacity. 

A "bit cell" is an abstract term referring to the nominal amount of time used to partition 
a bit-wide stream into component time-based values. Generation of the X-axis 
(reference clock) is the function of the host system controller. Without superimposing 
the X-axis, the value of the bit stream at a given time is impossible to determine. 
Figure 9-4 compares FM and MFM recording of a bit stream with a value of 01011001. 

9.3.1 Single Density (FM) 

Frequency Modulation (FM) is a self -clocking encoding scheme used to record bit serial 
data on magnetic media. Bit cell clocking is achieved by first writing a one bit flux 
reversal to define the leading edge of the cell. If the data value of the cell is a one, a 
second flux reversal will occur approximately midway through the bit cell. If it is a zero, 
there will be no further flux reversals until the leading edge of the next bit cell. The bit 
cell time for single density is four microseconds. The pulse width for a one bit (either 
clock or data) is 300 ns. See Figure 9-4. 

9.3.2 Double Density (MFM) 

Modified Frequency Modulation (MFM) is a bit serial encoding scheme used to record 
data on magnetic media. Unlike FM, MFM does not provide clocking pulses to create a 
cell. In MFM, the data window (bit cell) generation requires the host system floppy disk 
controller to derive a reference clock from the incoming data bit stream that can be 
used to define bit cell boundaries. The nominal bit cell time for MFM is two 
microseconds. See Figure 9-4. 

When using MFM, a write precompensation of 200 nanoseconds should be used by the 
floppy disk controller. 

9.4 SOFTWARE CONSIDERATIONS 

The following paragraphs address device driver software parameters and applications in 
order to optimize data throughput and storage capacity for the 525. 

9.4.1 Drive Selection 

To utilize all six data streams of the 525, the host controller should use a binary device 
(drive) selection on the drive interface bus. 

Use of a Radial Select mode, with Side Select, would limit the host system to selecting 
eight logical disk surfaces (i.e., one double-sided floppy disk drive and one 525). 

9AJ2 Addressable Tracks (Segments) 

Software drivers for the 525 should allow a track value of 255 to utilize all segments 
within a stream. 



9-4 



2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 
I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 h 



FM 



C CD C C D_ C D C C C D 

ir — ltltu — Lnnnru — u — ltlt~ 



D=0 D=1 D=0 D=1 D=1 D=0 D=0 D=1 



MFM 
to 



~~U LTU LTHJ~ 

D = D = 1 I D = I D = i|d = i|d=o|d = 0|D = i| 



2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 

X AXIS (TIME BASE IN /US) 

Figure 9-4. FM vs. MFM Recording 

9.4.3 Number Of Sectors 

Software drivers for the 525 must utilize the appropriate number of sectors per 
segment. (See Paragraph 9.5.) 

9AA Stream Formatting 

The operating system should format streams in consecutive pairs to reduce the time 
required for the verification pass. When Stream 2 is formatted after Stream 1, the 
controller can then start the verification pass for Stream 1 and then Stream 2. This way 
serpentine recording will not cause the loss of time required to recalibrate to Segment 
($. Another way to accomplish the same result is to format all six streams prior to the 
start of the verification pass. 

9.4.5 I/O Buffering & Sector Interleaving 

Multiple sector accessing should always be performed in a contiguous mode to avoid 
repositioning within segments. Therefore, there should be no sector interleaving. 

Although sector interleaving is often used by systems integrators, it does lengthen the 
interblock time between sectors that is required by certain Disk Operating Systems 
(DOS) to relocate data. Another performance penalty occurs when the rate at which the 
DOS can accept data is exceeded, causing the system to wait one full disk rotation 
before being able to retrieve the data written in the next consecutive sector. A similar 
penalty can occur when using the 525. It is caused by a host system not being able to 
sustain a data rate of 49.1 Kbytes/sec with 512 byte sectors. The time required for each 

9-5 



reposition is 1.7 seconds. Disk users facing this problem address the issue by interleaving 
sectors by the same factor. However, sector interleaving on tape would force the 525 to 
perform constant repositions. 

Fine tuning of the 525 to an Operating System can be accomplished by increasing the 
minimum gap size between sectors to achieve the correct Interblock Time. Using gap 
characters to compensate for the required Operating System Interblock Time eliminates 
the time penalty of a segment reposition at the expense of the users data capacity. 

Adding one byte to the Inter-Record Gap (JRG) G3 (see Figure 9-5) increases this time by 
16 us. Because the maximum available number of bytes per segment is 20,455 bytes, an 
increase of G3 could result in a smaller number of sectors per segment. Refer to 
Paragraph 9.5.1 for details. 

9.4.6 Retension Pass 

Tapes that have set idle, transported, handled excessively, or have been involved in more 
than 50 start/stop operations, should have a retension pass to ensure proper operation. 
Failure to do so may result in data error rates that are unacceptable. The 525 performs 
this function automatically when a tape is loaded into the device. The pass lasts for 
approximately 90 seconds. - Future 525a (January 1905) will h a ve a short auto"i , e. t ari3ion 
pq fio built into tho unit . This pass wi ll nlsn tnke place during a tape load) but will laot for 
e ppiuxiniulely 30 seconds 

Full retension passes can be performed under program control by seeking to segment 255 
and followed by a return Seek to segment 01 Full retension is a function of host software 
and should be performed when soft errors increase to an unacceptable level due to 
excessive start/stop operations or repositions. 

9.5 FORMATTING 

9.5. 1 Format Description 

In order to ensure interchangeabiiity between drives and proper operation over the entire 
operating temperature range, it is required to have preambles and postambles (gaps) 
attached to each sector. The use of the standard IBM System 34 format and MFM 
encoding is recommended. Formats deviating from the IBM standard must still comply 
with the minimum gap requirements specified for the IBM System 34 format. (See Figure 
9-5.) 



9-6 



The formula for the maximum number of sectors per segment for a given sector size is: 

SL- IP 
Sectors Per Segment = Qp + qj_ + jqj_ 

SL = Segment length (fixed) = 20,455 bytes 

IP = Index Postamble = 146 bytes (IBM format) 

DF = Data Field = 256 or 512 or 1,024 bytes 

OL = Overhead Length = 62 bytes (IBM format) 

IGL = Inter-record Gap Length G3 =54 bytes for 256/512 byte Data Fields 

84 bytes for 1,024 byte Data Fields 



Sector Length 


Sectors/Segment 


Capac i ty/Stream 


Total Formatted Capacity 


256 bytes 


54 


3.5 Mbytes 


21.15 Mbytes 


512 bytes 


32 


4.2 Mbytes 


25.07 Mbytes 


1,024 bytes 


17 


4.4 Mbytes 


26.63 Mbytes 



9-7 



STREAM FORMAT 



f 



'INITIAL 
O INDEX 
1 MARK 



.50" 



SEGMENT 
NO: 



+ .5" 
-0" 



INDEX 
MARK 



.34" 



1f 



Sf- 



INDEX 
MARK 



600 FEET 



SEGMENT 
NO: N 



INDEX 
MARK 



iJ- 



if 



INDEX 
MARK 



SEGMENT 
NO: 254 



RECOMMENDED 

SEGMENT 
FORMAT (MFM) 

Characters (HEX) written on tap* 
Sector size -> 1024, No. of byte* per field 
Sector size J 512. No. of bytes per field 
Sector sue = 25b, No. of bytes per field 



^■-- 

















26.55" + -j 




























^H 


r 












































































































V J 


POST 
INDEX 
MARK 

GAP 



SYNC 


u 

u 


'1 


GAP 

1 


SECTOR 

10 

SYNC 


f 


8 * 

o! 

< 


if 


II 


°1 


KX 

SI 


ID 
CRC 


GAP 

2 


M 


51 


ill 


USER 
DATA 


OATA 
CRC 


WRITE 
SPLICE 
GAP 

3 


o o 
fc9| 

Ml *> 


8 5 


8* 

< 


jjjl 


If 

EI 


P* 
si 




4E 


00 


C2 


FC 


4E 


00 


A1 


FE 


(SG (ST (SC 

NO.) NO.) NO.) (SCL) (CRC) 4E 00 


A1 


FB 




(CRC) 4E 


00 


A1 


FE 






.>> 


80 


12 


3 


1 


50 


12 


1 


1 


1 1 1 (03) 2 22 12 


3 


1 


1024 


2 84 


12 


1 


1 








80 


12 


3 


1 


50 


12 


1 


1 


1 1 1 (02) 2 22 12 


3 


1 


512 


2 54 


12 


1 


1 








80 


12 


3 


1 


50 


12 


1 


1 


1 


1 


1 


(01) 


2 


22 


12 


3 


1 


256 


2 


54 


12 


1 


1 











ON 



1 — BRACKETED FIELDS REPEATED FOR ALL SECTORS ' NEXT SECTOR J H 



FORMATTED 
CAPACITIES 



SECTOR SIZE SECTOR/SEGMENT USER BYTES/SEGMENT 



DATA YIELD PER STREAM 



TOTAL DATA YIELD 



1024 Bytes 
512 Bytes 
256 Bytes 


17 
32 
54 


17,408 Bytes 
16,384 Bytes 
13,824 Bytes 


4.4 M Bytes 
4.2 M Bytes 

3.5 M Bytes 


26.63 M Bytes 
25.07 M Bytes 
21.15 MBytes 



Figure 9-5. IBM System 34 Format Example 



It is important to use controllers offering maximum versatility. Some floppy disk 
controllers allow only 15 sectors of 512 bytes each to be formatted per segment. Others 
may not allow all 255 segments to be addressed. Limitations to these parameters would 
significantly impact capacity and performance of a system. 

9.5.2 Data Integrity 

The 525 is a streaming device that has the ability to re-write individual sectors. Host 
operations should be designed to run this device in a streaming mode as much as possible. 

System operations designed strictly for a start /stop operation will cause heat build up 
within the cartridge and the tape device. This heat has to be removed through external 
cooling (fan(s)). Failure to do so will lead to a rise in temperature that may exceed 45° 
at the cartridge base, and loss of data could result. 

To ensure data integrity, the following steps should be taken by the host system: 

1. Format each stream with the selected sector scheme. An all-ones pattern should be 
written in the user data field to test all bit cells within the user data area. 

2. Run a verification pass against each formatted stream to test for dropout events 
which result in CRC errors. Any sector with CRC errors should be flagged in the 
Volume Table Of Contents (VTOC) to indicate a defective sector. This prevents 
future use of defective sectors. 

Each of the above passes takes approximately 90 seconds per stream to complete. 

9.5.3 Format Operation 

The 525 appears as a soft sectored floppy disk drive to the Floppy Disk Controller (FDC). 
Consequently, the format to be recorded is determined by the FDC. During formatting, 
the FDC scans for an Index pulse on the drive interface. When detected, the FDC is to 
start writing the track format, beginning with the Index postamble gap, and followed by 
the required numbers of sectors, including IDs. After the last sector, the FDC resumes 
writing the fill field (Index preamble gap) until another Index pulse occurs. Upon 
detection of the Index pulse, the FDC must stop the Write operation. The fill field 
allows the open loop writing process to be consistent with speed variations, and therefore 
Index timing, of the 525. The minimum time between Index pulses, while formatting, is 
327 ms. Upon completion of the formatting operation, a verification pass should be run 
against each stream. (See Figures 9-6, 9-7 and 9-8.) 



9-9 



(JED 



SELECT 
DESIRED 
STREAM 



ISSUE 

RECALIBRATE 

COMMAND 




BUILO 
SEGMENT IMAGE 





EXECUTE 

WRITE SEGMENT 

COMMAND 




ISSUE 
STEP PULSE 



INCREMENT 
SEGMENT IMAGE 



FORMAT 
COMPLETE 



Figure 9-6. Format Flowchart 



SELECT 
0ES1REO 
STREAM 



ISSUE 
RECAU8RATE 
COMMAND 




log errors 
return 



£ 



INITIATE 
SECTOR COUNT 



REAO 
SECTOR 




Figure 9-7. Verification Pass Flowchart 



9-10 



SELECT 



T1 



HEAD LOAD/ 
MOTOR ON 



INDEX 



WRT GATE 



WRTDATA 



T2 



T3 T5 



T4 



T6 



■* 5- 



4 5- 



T7 T12 T14 T17 



T8 



T15 



T16 



DIRC 



STEP 



-5 fr- 



T9 T13 



T10 T11 



u 



T 1 -*T 2 Select to HLD/MTOnJ> 0. 

T 2 - T 3 HLD/MTON to INDEX> 350 ms. 

T 3 *T^ INDEX to WRT GATE< 125 jjs. 

6 



T^ h>T a WRT GATE to WRT DATA< 4 jxs. 



•T 5 INDEX Width = 1.7 ms min. 



T^ ->T 7 Segment Boundaries = 327 ms min. 
T 7 -+T g INDEX to WRT GATE_^>0. 
T ? -*T Q INDEX to DIRC>0. 
To -*T, n DIRC to STEE> 1 ps. 



T 10 "* T li STEP Width = 1 P s min# 

T ll "* T 13 STEP false t0 DIRC = 10 H s min * 

T ll >T 14 STEP false to INDEX = 10 ° V s min * 
T 7 -*T \n Inter-Segment Gap = 6 ms H»ift. «aax, 



Figure 9-8. Stream Format Timing 



9-11 



9.6 ACCESS TIMING 

9.6.1 Stream To Stream 

To achieve optimum positioning accuracy, the Read/Write head positioner is always 
returned to home position prior to positioning to a new stream. 



HOME POSITION i 


: t 


TRACK 1 i 


TRACK 2 i 
TRACK 3 i 


f R/W 
1 1 HEAD 


TRACK 4 i 


1 v*. 1 


TRACK 5 i 


: i 


TRACK 6 ( 



Figure 9-9. Head Positioning 

Each step requires 200 ms. 

Example: Position from Track 1 to Track 3 = & x 200 = 4Jt)0 ms. 

Track 1 to Homo. Position = 200ms, tiomr Position to Track 3 = l£00ms 

9.6.2 Segment To Segment 

Access time from a segment to a contiguous segment is 344 ms. (Index Mark to Index 
Mark). 

Access time from a segment to a non-contiguous segment is calculated by determining 
the offset number of segments between the "at" segment and the "target" segment and 
multiplying by 0.344 seconds. This technique is illustrated in the following examples and 
Figures 9-10 and 9-11. 

A. Upstream Segment Accessing 
Target Segment 166 
At Segment _150 
Offset 16 

Access Time = (16) x (0.344) = 5.5 seconds 

B. Downstream Segment Accessing 
At Segment 64 
Target Segment J>8 
Offset Number 6 

Access Time = (6) x (0.344) +1.2 (ramp time) = 3.26 seconds 

9-12 



T1 
DRVSL ^^ 

T2 
I 

S/S 



HEAD LOAD / 1 T3 

MOTOR ON I 



LF ™u 



INDX T4| |T5 T10 I I T12 



DIRC 



STEP T8 I I T9 



u 



RD DATA T6| SEGMENT N jj T1 1 SEGMENT N + 1 | 



T, - Host asserts DRVSL lines. 

T~ - Host asserts S/S line. 

T 3 - Host asserts HLD/MTO line. 

T^ - 525 asserts INDX, T 3 + T^ = 400 ms min. 

T. - 525 de-asserts INDX, T4 *Tr = 1.7 ms min. 

TV - 525 begins to supply raw data, T. -►T X^2 ^is. 

Tj - Host sets DIRC line in preparation for a Step In command, Tc -+7j<C33& ms. 

T~ - Host sets STEP line, T ? -*T^>1.0 jjis and T 5 -*T 9 <338 ms. 

Tq - Host resets STEP Tg -*TJ> 1 ^s. 

T 1Q - 525 asserts INDX, T^ -+T {Q = 338 ms. 

T, , - Same as T6. 

T| 2 - 525 resets INDX, T, Q -*T 12 = 1*7 ms min. 



Figure 9-10. Contiguous Segment-to-Segment Timing 



9-13 



9-6.3 Read Reposition 







SEGMENT BEING 
ACCESSED 










SEGMENT N - 1 


1 

M 


SEGMENT N 


1 

M 


SEGMENT N + 1 


1 

M 





TT 



T 2 . . T3 



Tl 



sw 

Jt 



T9 



T10 



I >X 4 ) 



T1 



INDX 



EFFECTIVE CAPSTAN OPERATION 

T9 T11 



u 



u 



T2 



T10 



RD DATA 



I 



SEG N DATA 



SEG N DATA 



n 



SEG N+1 DATA 



STP 



DIR 



— LT 



IT 



T, - 525 generates INDX pulse (begins valid Read Data time). 
Ty - Conclusion of valid RD time, T. -*>T <^ 340 ms. 

(To keep the 525 streaming, the host must send a STP pulse within T, -*T^ = 344 

ms.) 
To - No Step pulse sent by host, 525 drive motor begins to ramp down, T 2 -»To = 6 ms. 
T^ - Tape motion halts T- -*T. = 300 ms. Tape motion starts in reverse. 
T 5 - Tape motion in reverse at full speed, T^ ->T ,- = approximately 350 ms (Ramp-up 

time). 
T, - 525 runs reverse, T 5 -VT, = 350 ms. 

T 7 - 525 starts ramp-down, T. -*T 7 = approximately 300 ms. 
T« - Tape motion at Read speed, T-, -*Tg = approximately 350 ms. 
Tq - 525 generates INDX pulse (same as T.). 
T.q - Same as T-. 
T . . - Same as T.. 

Figure 9-11. Read Reposition Timing 



9-14 



APPENDIX A 
CONFIGURATION TABLES 

A. 1 JUMPER OPTIONS 

Jumpers Wl through W10 are used to configure the 525 as follows: 

Wl - Stream selection jumper 

W2 - Stream selection jumper 

W3 - Stream selection jumper 

W4 - In Use LED on when logical drive selected 

W5 - In Use LED on when logical drive selected and Head Load line true and drive 
ready 

W8 - When in, allows host generated signal to light front panel LED to indicate drive 
in use 

W9 - Service aids configuration jumper 

W10 - Service aids configuration jumper 

A.2 STREAM SELECTION TABLES 

Stream Selection is provided by the four Drive Select (DS 1-4) lines together with the 
Side Select line, as determined by the configuration of jumpers Wl, W2 and W3. 

Option 1. Binary Select Using DS2 - DS* 



Wl 


-In 


W2- 


-In 


W3-fci 


Yields 


DS1 


DS2 


DS3 


DS* 


Side Select 




H 


L 


H 


H 


H 


Stream 1 


H 


H 


L 


H 


H 


Stream 2 


H 


L 


L 


H 


H 


Stream 3 


H 


H 


H 


L 


H 


Stream 4 


H 


L 


H 


L 


H 


Stream 5 


H 


H 


L 


L 


H 


Stream 6 



A-'l 



Option 2. Binary Select Using DS1 - DS3 



Wl 


-Out 


W2- 


-In 


W3- 


In 


Yields 


DS1 


DS2 


DS3 


DS4 


Side Select 




L 


H 


H 


H 


H 




Stream 1 


H 


L 


H 


H 


H 




Stream 2 


L 


L 


H 


H 


H 




Stream 3 


H 


H 


L 


H 


H 




Stream 4 


L 


H 


L 


H 


H 




Stream 5 


H 


L 


L 


H 


H 




Stream 6 



Option 3. Radial Select Using DS2 - DS4 And Side Select 



Wl- 


-In 


W2- 


-Out 


W3-In 


Yields 


DS1 


DS2 


DS3 


DS4 


Side Select 




H 


L 


H 


H 


H 


Stream 1 


H 


L 


H 


H 


L 


Stream 2 


H 


H 


L 


H 


H 


Stream 3 


H 


H 


L 


H 


L 


Stream 4 


H 


H 


H 


L 


H 


Stream 5 


H 


H 


H 


L 


L 


Stream 6 



Option 4. Radial Select Using DS1 - DS3 And Side Select 



Wl- 


-Out 


W2- 


-Out 


W3-In 


Yields 


DS1 


DS2 


DS3 


DS4 


Side Select 




L 


H 


H 


H 


H 


Stream 1 


L 


H 


H 


H 


L 


Stream 2 


H 


L 


H 


H 


H 


Stream 3 


H 


L 


H 


H 


L 


Stream 4 


H 


H 


L 


H 


H 


Stream 5 


H 


H 


L 


H 


L 


Stream 6 



A-2 



Option 5. Binary Select Using DS1 - DS2 And Side Select 



Wl 


-In 


W2- 


-In 


W3 - Out 


Yields 


DS1 


DS2 


DS3 


DS4 


Side Select 




L 


H 


H 


H 


H 


Stream 1 


L 


H 


H 


H 


L 


Stream 2 


H 


L 


H 


H 


H 


Stream 3 


H 


L 


H 


H 


L 


Stream 4- 


L 


L 


H 


H 


H 


Stream 5 


L 


L 


H 


H 


L 


Stream 6 



Option 6. Binary Select Using DS2 - DS3 And Side Select 



Wl- 


-Out 


W2- 


-In 


W3 - Out 


Yields 


DS1 


DS2 


DS3 


DS4 


Side Select 




H 


L 


H 


H 


H 


Stream 1 


H 


L 


H 


H 


L 


Stream 2 


H 


H 


L 


H 


H 


Stream 3 


H 


H 


L 


H 


L 


Stream 4 


H 


L 


L 


H 


H 


Stream 5 


H 


L 


L 


H 


L 


Stream 6 



Option 7. Binary Select Using DS3 - DS4 And Side Select 



Wl 


-In 


W2- 


-Out 


W3 


-Out 


Yields 


DS1 


DS2 


DS3 


DS4 


Side Select 




H 


H 


L 


H 




H 


Stream 1 


H 


H 


L 


H 




L 


Stream 2 


H 


H 


H 


L 




H 


Stream 3 


H 


H 


H 


L 




L 


Stream 4 


H 


H 


L 


L 




H 


Stream 5 


H 


H 


L 


L 




L 


Stream 6 



A-3 



A.3 SERVICE AIDS 

The on-board microprocessor can be utilized to perform basic service aid routines with 
the 525. The service aids are initiated by applying ground jumpers W9 and W10. 

A.3.1 Continuous Forward /Reverse 

With jumper W9 installed, inserting a cartridge causes the drive to do a normal retension 
pass and then start a continuous forward/reverse cycling between BOT and EOT. Head 
position is changed at the end of each pass to equalize wear. This function is terminated 
by removing the jumper and the cartridge. 

A.3.2 Stream Positioning - All Streams 

With jumper W10 installed, inserting a cartridge causes the head to move to the home 
position. Then the head moves alternately between the home position and each stream 
position, first decrementing, then incrementing, with a one second delay at each 
position. The function is terminated by removing the jumper and the cartridge. 

A.3.3 Stream Positioning - Stream & 4 

With jumper W10 installed, inserting a cartridge starts the routine outlined in Paragraph 
A.3.2. Subsequent insertion of W9 modifies the routine as follows: The head will 
alternate between the home position and Stream 4 only. The head will remain two 
seconds at Stream 4, but turnaround without delay at the home position. Removal of 
W10 causes the head to remain at Stream k until W10 is replaced. The function is 
terminated by removing the jumpers and the cartridge. 

A.3.4 Cyclic Tape Motion 

With jumpers W9 and W10 installed, inserting a cartridge causes the drive to do a normal 
retension pass and then start a cyclic run forward motion for approximately 500 
milliseconds (ms), then run in reverse for approximately 125 ms. This cycle continues 
until EOT is reached. Then, the drive does a high speed reverse to BOT and starts the 
cycle over. This function is terminated by removing the jumpers and the cartridge. 



A-4 



APPENDIX B 
OPERATING PARAMETER CONSIDERATIONS 



Integration of the 525 into a host floppy disk control system requires consideration of 
several specific operating parameters. Parameter changes indicated in this Appendix 
reflect the use of either Western Digital 179X, 279X, or NEC 765 controller chips by the 
host system. 

B.1 TIMEOUTS 

Two types of time outs may require adjustment for the 525. 

The first time out is sometimes referred to as the "dead man" timer. This timer is used 
by the host system to test for a catastrophic device failure. Common implementation of 
this timer is to start its count when the drive is first accessed, and halt it with the Index 
pulse returned by the drive. Because this timer is external to both types of controller 
chips, it may become a software consideration for the host system. The nominal time for 
the 525 to generate an Index pulse is 1.7 seconds from the time that the motion signal 
(Motor On or Head Load) is asserted. Any system time out shorter than 1.7 seconds 
should be adjusted to reflect this parameter. 

The second type of time outs are those internal to a specific floppy disk controller chip. 
These time outs are either specified as part of commands (WD), or as part of a Specify 
Command (NEC), used to set up the controller prior to an operation. 



Type 


NEC 765 


WD179X 


WD279X 


Head Load 


2 ms 


ms 


ms 


Step Rate 


1 ms 


3 ms 


3 ms 


Head Seek 


N/A 


Null Seek* 


Null Seek* 



* The WD controller chips keep the head loaded for 15 "revolutions" (15 Index pulses) 
after the last command. To avoid constant repositioning during this time, a Null 
Seek command should be issued at the completion of all tape movement operations. 
This is accomplished by Seeking the current segment with the HLD bit turned off in 
the Seek command. 

B.2 READ AFTER WRITE 

The normal Read- After-W rite operation for a floppy disk drive must be modified to 
achieve optimum performance with the 525. Read verification following a format pass 
should be performed in a streaming mode. System integrators should modify their format 
routine to format adjacent streams in pairs (i.e., 1 + 2, 3 + 4, 5 +6) to eliminate the dead 
time caused by recalibrating to logical Track 00 (Segment 0). The read verification 
following the format pass should be performed in the same manner. 



B-l 



B.3 



REINSTRUCT TIMING 



The most critical timing for the 525 is in the format operation. Following the 
termination of a Write track operation by an Index pulse from the 525, the host 
controller has six milliseconds in which to give the drive a Step pulse to avoid a 
reposition. It is recommended that when the controller completes the Write Track 
command, the host system should immediately initiate a Step command. Following the 
Step command the host should then up-date the "Track Image Buffer" (Western Digital) 
or the "Track Sector List" (NEC 765) in preparation for the next segment format 
operation. To ensure streaming operations when editing sectors or segments following 
formatting, the host system must perform all Step In or Step Out type functions with the 
HLD bit turned on and the Verify bit (WD only) turned off. 



B.4 



SECTORS/SEGMENT COUNTS 



In order to utilize the full capacity of the 525, the following parameters in the device 
driver software and format routine should be modified: 

o Number of Segments/Stream (equivalent to Tracks/FD surface) 
o Number of Sectors/Segment (equivalent to Sectors/FD track) 

The following table is based on MFM encoding and an IBM System 34 type compatible 
format. The Bytes/Sector column lists the standard sector sizes used for floppy disks. 
The Sec tors /Segment column reflects the maximum number of sectors that may be 
recorded reliably within a segment. The Segments/Stream columns state the maximum 
segment count that the floppy disk controller chip can support. 



Bytes/ 
Sector 


Sectors/ 
Segment 


Segments/ 
Stream (WD) 


Segments/ 
Stream (NEC) 


256 


54 


252* 


255 


512 


32 


252* 


255 


1024 


17 


252* 


255 



B.5. 



*WD controller chips use the following hexadecimal numbers as control bytes 
for initialization purposes: F5 (245 dec), F6 (246 dec), F7 (247 dec). They are, 
therefore, unusable as valid segments for data storage. 

STREAM (DRIVE) SELECTION 



Adjacent streams run in opposite directions, allowing integrators to utilize the 
advantages of serpentine recording. The 525 has three configuration jumpers (Wl, W2, 
W3) that facilitate the mapping of the six streams to the Drive Select and Side Select 
lines. (See Appendix A for configuration tables.) Two configurations allow for a radial 
selection of stream pairs with the Side Select choosing the required stream. In this 
mode, the 525 most closely resembles three double-sided disk drives. However, the head 
of the 525 is not at the same position in relation to Track 00 as it would be on a floppy 
disk. That is, if a double-sided floppy disk head is stepped to Track 23, both heads (side 
A and side B) would be over the same physical position except on opposite sides of the 
floppy disk media. This is not true for the 525. 



B-2 



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